The present invention relates to an electronic control method and apparatus for internal combustion engines, and more particularly to an electronic ignition control method and apparatus of the type including a calculation circuit to calculate optimum timing of sparks supplied to the engine in accordance with changes of the operating condition of the engine.
In conventional electronic ignition control devices of the type, generally negative pressure in the intake manifold and rotation speed of the engine are electrically detected to calculate optimum engine spark timing. The spark timing is controlled by an output signal indicative of optimum spark advance which is calculated from detected signals indicative of the negative pressure and the rotation speed. Furthermore, a predetermined period of time necessary for energization of an ignition coil primary winding is considered as a factor in the factor in the calculation to set optimum spark timing. This means that the calculation is very complicated and at least two detecting elements for detecting changes of the operating condition of the engine are required.